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Petalite [abbr. Ptl ]

Year of discovery: 1800 (Utö mines, Sweden), 1945 (Japan)

Locality list: A locality of petalite

• LiAlSi₄O₁₀
• [Li⁺][Al³⁺][(Si₂O₅)₂]^4-

• Class: Phyllosilicate
• Insoluble in: HCl, HNO₃, H₂SO₄
• Fluorescence: Thermoluminescence

• Color: Colorless, White
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Thick tabular

• Cleavage: Perfect on {001} (1 plane), Poor on {201} (1 plane)
• Hardness: 6.5
• Density: 2.4

• System: Monoclinic
• Group: 2/m, P2/a
• Lattice: a=11.7, b=5.2, c=7.6, β=112.5